CN115073122A - Straw aerogel flame-retardant insulation board and preparation method thereof - Google Patents

Abstract

The invention discloses a straw aerogel flame-retardant thermal insulation board and a preparation method thereof. The straw aerogel flame-retardant insulation board of the present invention is obtained by mixing straw raw material, coupling agent, water-soluble silicon source, calcium source and water uniformly, paving and pre-pressing, and then solidifying at high temperature and high pressure; the straw The fibers are composed of long straw fibers with a length of 1-2 cm and short straw fibers with a length of less than 1 cm. The straw aerogel flame-retardant insulation board of the invention not only retains the natural texture of the straw, has a good decorative effect, but also has the advantages of light weight, high strength, smooth surface, flame retardant, light weight, no formaldehyde, heat insulation and sound insulation and mildew resistance. Anti-moth and other features.

Description

A kind of straw aerogel flame retardant insulation board and preparation method thereof

technical field

The invention relates to a straw aerogel flame-retardant thermal insulation board and a preparation method thereof, belonging to the technical field of novel composite fiber boards.

Background technique

my country ranks first in the world in terms of production and consumption of wood-based panels, and is a big producer of wood-based panels. However, forestry resources are relatively short. The per capita forest area is only 1/4 of the world's per capita level. The external dependence of wood is close to 50%. few.

my country is also a big agricultural country, with abundant crop straw resources, huge output, variety and wide distribution. The use of crop straw in the field of wood-based panel production can not only solve the problem of wood shortage, but also promote the utilization of straw resources.

The Chinese Patent Publication No. CN104724976A discloses a straw fireproof thermal insulation board and a production method thereof. The present invention uses straw as the main filling material, and makes full use of the straw's characteristics of strong filling ability, high fiber toughness and high fireproof and thermal insulation ability. Under the action of particles, latex powder and water repellent, a thermal insulation board with strong bending, compressive and flexural resistance, high fire rating, convenient construction and low cost is produced. At the same time, it also solves the problem of post-processing of agricultural waste. and reuse issues. The method uses phenolic resin as the adhesive, which will lead to the problem of formaldehyde release during the production and use of the template, and has no formaldehyde-free feature.

The Chinese Patent Publication No. CN103626433A discloses a straw insulation board and a preparation method thereof. The present invention includes a core material layer and a coating layer. The core material layer is mainly pressed by epoxy glue, jade powder, pearl sand and straw. It is prepared by molding, and the surface coating layer mainly uses the inorganic cementing material with bonding function to evenly coat the surface layer of the straw board, so as to obtain a new type of straw insulation board with straw as the board; the new type of straw insulation board has fast It has excellent properties such as molding, heat insulation, flame retardant, mildew resistance, and high strength. The core surface layer of the thermal insulation board prepared by the method has different materials and different thermal expansion coefficients, which may cause problems such as cracking during use, and at the same time, the flame retardant performance of the core layer is also weakened.

The Chinese patent publication number CN113084960A introduces a corn stalk board and its preparation method. The method utilizes stalk softening enzymes to etch the surface of the long fibers of the corn stalks to expose the coarse stalk fibers, and uses the stalks with rich stalks. Pore structure, using nanocellulose solution as a reinforcing agent to improve the strength of the sheet. This method has low efficiency in treating straw, and the conditions of enzymatic reaction are relatively severe, so it is difficult to be applied on a large scale.

The Chinese Patent Publication No. CN111300565A introduces a preservative corn stalk reconstituted material and a manufacturing method thereof. The method uses resorcinol-modified phenolic resin as an adhesive to disperse and anti-corrosion the corn stalk husk. The composite panels prepared by this method do not have the characteristics of flame retardancy and aldehyde-free.

The Chinese Patent Publication No. CN112851290A introduces a wood and straw fiberboard using inorganic adhesives and a preparation method thereof. The fiber content of the straw fiberboard prepared by the method is relatively low, the woodiness of the board is poor, and the density of the sample board is high. Does not have the characteristics of light weight.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a straw aerogel flame-retardant thermal insulation board and a preparation method thereof. It solves the biggest problem of straw flammability and broadens the application field of straw composite board.

The scheme that the present invention solves the above-mentioned problem is as follows:

The invention provides a straw aerogel flame-retardant thermal insulation board, which is obtained by mixing straw raw materials, coupling agents, inorganic materials and water uniformly, then paving and pre-pressing, and then being solidified at high temperature and high pressure; the inorganic materials include: Water-soluble silicon source and calcium source;

The parts by weight of the above-mentioned components are as follows:

The mass ratio of the water to the inorganic material is 0.8-1;

The process parameters of the high temperature and high pressure solidification are: the temperature is 160-220°C, the unit pressure is 3-10MPa, and the solidification time is 10-30min;

The straw raw material is composed of long straw fibers and short straw fibers, wherein the long straw fibers account for 10% to 30% by weight, and the short straw fibers account for 70% to 90%; 2cm, and the length of short straw fibers is less than 1cm;

The moisture content of the straw raw material is less than 10wt%.

The coupling agent is polyvinyl alcohol; the addition of the coupling agent can improve the bonding performance between the inorganic adhesive and the straw, and improve the interface compatibility.

The water-soluble silicon source is instant powdery sodium silicate, and the modulus is 2.1-3.4; in actual use, the solid content after being configured into an aqueous solution is 30%-40%.

The calcium source is hemihydrate gypsum; the calcium source is a reinforcing agent, and the addition of the calcium source can react with the water-soluble silicon source to generate calcium silicate crystals, thereby enhancing the mechanical properties of the board.

The invention adopts a double-adhesive system which is a composite of silicon aerogel and cellulose aerogel. The water-soluble silicon source in the present invention can be uniformly mixed with the straw fiber raw materials, and in the process of high temperature and high pressure, a silica aerogel network is formed to bond the straw fiber raw materials together; at the same time, the lignin and Cellulose is also entangled and reacted at high temperature to form a cellulose aerogel network, which further improves the internal bonding strength of the sheet. Adding coupling agent polyvinyl alcohol in the present invention can improve the interface compatibility between silicon source and straw; adding calcium source can react with silicon source and water vapor under the conditions of high temperature and high pressure to generate calcium silicate crystals, which can be deposited on the board. The inside plays the role of strengthening the bones and improving the mechanical properties of the board; at the same time, the evaporation of water vapor under high temperature conditions can form pores in the board, forming a complex pore structure, which is conducive to reducing the density of the board and improving the thermal insulation performance of the board. The calcium-silicon system reacts further to improve the mechanical strength of the sheet.

The straw fiber raw material used in the present invention selects the mixing of long straw fibers and short fibers, in order to mix the straw fibers and the inorganic adhesive evenly, so as to promote the compact structure of the board and improve the mechanical properties of the board. The long straw fibers in the board overlap each other to form a network structure interwoven vertically and horizontally, which can inhibit the generation and spread of micro-cracks in the inorganic gel system, improve the elastic modulus of the board, and at the same time retain the natural shape of the straw; The fiber has a large specific surface area and is more easily infiltrated by the water-soluble silicon source. After mixing evenly, it is filled inside the board to improve the internal bonding strength of the board, thereby effectively improving the mechanical properties of the board.

In order to realize the above technical solution, the preparation steps of the straw aerogel flame-retardant insulation board of the present invention are as follows:

(1) After the straw is dedusted, it is dried, and subjected to mechanical grinding to obtain fiber filaments of different lengths. After screening, the required long straw fibers and short straw fibers are obtained, and the long and short fibers are compounded in proportion to become straw raw materials;

(2) First, weigh the water-soluble silicon source, calcium source, step (1) straw raw material, polyvinyl alcohol and water in proportion, secondly prepare the water-soluble silicon source and water into an aqueous solution, and finally mix the straw raw material with polyvinyl alcohol in sequence , the water-soluble silicon source solution and the calcium source are stirred and mixed to obtain a mixed material;

(3) obtaining the slab of the straw aerogel flame-retardant thermal insulation board after the mixed material of step (2) is pre-pressed by paving and solidified at high temperature and high pressure;

(4) Step (3) After curing, trimming, and sanding the slab obtained in step (3), the finished straw aerogel flame-retardant thermal insulation board according to the present invention is obtained.

The length of the mechanically ground straw fibers in step (1) is not more than 2 cm.

The operating conditions of the pre-compression molding in step (3) are normal temperature and normal pressure, and it can be pressed until the slab is formed.

The beneficial effects of the present invention are as follows:

(1) The straw aerogel flame-retardant insulation board of the present invention not only retains the natural texture of the straw, has a good decorative effect, but also has the technical characteristics of light weight, high strength, smooth surface, and flame resistance, which is conducive to promoting the straw resource utilization.

(2) The straw aerogel flame-retardant insulation board of the present invention can reach B1 level flame-retardant, and has the characteristics of light weight, no formaldehyde, heat insulation, sound insulation, mildew and moth resistance, and the like.

(3) Using the components of the present invention to prepare the board under high temperature and high pressure conditions is conducive to reducing the density of the board and improving the thermal insulation performance of the board;

(4) The present invention uses long and short fiber composite straw fiber raw materials to fill the interior of the board, so that the straw fiber and the inorganic adhesive are evenly mixed, thereby improving the internal bonding strength of the board, thereby effectively improving the mechanical properties of the board.

Description of drawings

FIG. 1 is a schematic diagram of the surface structure of the thermal insulation board prepared in Example 1 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the present invention. not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1 to 2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 2:8 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 150g of gypsum, 6g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material is placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MP hot press to set a thickness of 0.9cm, and hot-pressed for 12 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

FIG. 1 is a schematic diagram of the surface structure of the thermal insulation board prepared in Example 1. From the figure, it can be found that the surface of the board is flat while retaining the natural texture of straw.

Example 2

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1 to 2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 2:8 1000g of straw raw materials were weighed;

(2) Weighing 200g of sodium silicate, 120g of gypsum, 5g of polyvinyl alcohol, and 260g of water respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material is placed in a 55cm×55cm mold and formed, and then placed on a 160°C, 7MP hot press to set a thickness of 0.9cm, and hot-pressed for 30 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 3

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1 to 2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 2:8 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 150g of gypsum, 6g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material is placed in a 55cm×55cm mold and formed, and then placed on a 220°C, 3MP hot press to set a thickness of 0.9cm, and hot-pressed for 8 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 4

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 3:7. 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 150g of gypsum, 6g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 12 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 5

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 3:7. 1000g of straw raw materials were weighed;

(2) Weighing 400g of sodium silicate, 150g of gypsum, 6g of polyvinyl alcohol, and 440g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 12 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 6

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 3:7. 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 150g of gypsum, 12g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 12 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 7

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long fibers with different lengths. After screening, long fibers with a length of 1 to 2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 1:9 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 120g of gypsum, 6g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 12 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Example 8

The preparation method of the straw aerogel flame-retardant thermal insulation board according to the present invention comprises the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long and different fiber filaments. After screening, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. The long and short fibers are 3:7. 1000g of straw raw materials were weighed;

(2) Weighing 370g of sodium silicate, 150g of gypsum, 6g of polyvinyl alcohol, and 420g of water, respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source, and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material is placed in a 55cm×55cm mold and formed, and then placed on a 200°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 10 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Comparative Example 1 (without calcium source)

A preparation method of a straw aerogel flame-retardant thermal insulation board, comprising the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long fibers of different lengths. After sieving, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. fiber;

(2) respectively weighing 370 g of sodium silicate, 6 g of polyvinyl alcohol, and 420 g of water, and stirring the straw fibers with the polyvinyl alcohol solution, the water-soluble silicon source and the calcium source in turn, and after mixing uniformly, a mixed material was obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 8 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Comparative example 2 (the rice straw is all short fiber)

A preparation method of a straw aerogel flame-retardant thermal insulation board, comprising the following steps:

(1) After the straw is dedusted, it is dried, and subjected to mechanical grinding to obtain different long fiber filaments. After sieving, short fibers with a length of less than 1 cm are obtained, and 1000 g of straw short fiber raw materials are weighed;

(2) Weighing 370g of sodium silicate, 6g of polyvinyl alcohol, and 420g of water respectively, the straw raw material is stirred with polyvinyl alcohol solution, water-soluble silicon source and calcium source in turn, and after mixing uniformly, a mixed material is obtained;

(3) The mixed material was placed in a 55cm×55cm mold and formed, and then placed on a 180°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 8 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Comparative Example 3 (reduce the temperature)

A preparation method of a straw aerogel flame-retardant thermal insulation board, comprising the following steps:

(1) After the straw is dedusted, it is dried and decomposed by mechanical grinding to obtain long fibers of different lengths. After sieving, long fibers with a length of 1-2 cm and short fibers with a length of less than 1 cm are obtained. fiber;

(2) respectively weighing 370 g of sodium silicate, 6 g of polyvinyl alcohol, and 420 g of water, and stirring the straw fibers with the polyvinyl alcohol solution, the water-soluble silicon source and the calcium source in turn, and after mixing uniformly, a mixed material was obtained;

(3) The mixed material is placed in a 55cm×55cm mold and formed, and then placed on a 120°C, 3MPa hot press to set a thickness of 0.9cm, and hot-pressed for 8 minutes to make a straw aerogel flame retardant thermal insulation package. blank;

(4) After curing the slab at room temperature for 3 days, trimming and sanding to obtain a finished slab.

Performance Testing

The performance tests were carried out on the sheets obtained by the embodiments of the present invention and the comparative examples, and the results are shown in Table 1.

Table 1 Performance test results of flame-retardant wood substrates

From the data of flexural strength and compressive strength of each embodiment and comparative example in Table 1, it can be found that in each embodiment of the present invention, the long fibers retain the macroscopic mechanical properties of straw, and the content of long fibers is appropriately increased, which is beneficial to the board. Improved mechanical properties.

It can be seen from Table 1 that an appropriate increase in temperature is beneficial to the improvement of the mechanical properties of the sample. At the same time, at high temperature, the wood in the organic matter is dehydrated and condensed, which improves the water resistance of the sample, which is manifested as a decrease in the expansion ratio of the water absorption thickness of the sample.

It can be found from the data in Table 1 that it can be seen in Examples 4 and 5 that appropriately increasing the ratio of silicon to calcium (increasing the content of sodium silicate and reducing the content of gypsum) is conducive to the transformation of the strength phase crystal of the inorganic material from the hydrated C-S-H crystal form into a crystal. A higher degree of tobermorite crystal, which is beneficial to the improvement of the mechanical properties of the sheet.

It can be seen from Examples 6 and 8 that increasing the temperature can promote the glass transition of hemicellulose and lignin in the straw, promote the formation of cellulose aerogel, facilitate the dehydration condensation reaction of hydroxyl groups, and improve the hydrophobicity of the board.

It can be seen from Comparative Example 1 and Example 1 that calcium source, as a curing agent for silicon source, can form hydrated calcium silicate crystals under high temperature and high pressure conditions, thereby improving the mechanical properties of the plate, losing the calcium source and reducing the mechanical properties of the plate. decreased significantly.

It can be seen from Comparative Example 1 and Example 2 that the overlapping method of long and short fibers can effectively improve the mechanical properties of the board, reduce the water absorption thickness expansion rate of the board, and reduce the slag problem of the board.

It can be seen from Comparative Example 3 and Example 1 that when the temperature is low (120°C), the glass transition degree of lignin and hemicellulose inside the straw is not enough, and the strength of the formed cellulose aerogel is weak, thus affecting the insulation board. mechanical properties and thermal insulation properties. At the same time, at low temperature (120 °C), the silicon source and calcium source generate calcium-rich C-S-H gel, and at 140 °C, low-crystallinity tobermorite crystals are formed, and at 180-200 °C, it gradually transforms to form a good crystallinity. of tobermorite crystals.

Claims (10)

1. The utility model provides a straw aerogel fire-retardant heated board which characterized in that: uniformly mixing straw raw materials, a coupling agent, an inorganic material and water, paving, prepressing, forming, and then solidifying at high temperature and high pressure to obtain the straw composite material; the inorganic material comprises a water-soluble silicon source and a calcium source;

the weight parts of the components are as follows:

the mass ratio of the water to the inorganic material is 0.8-1;

the technological parameters of the high-temperature high-pressure solid mold are as follows: the temperature is 160-220 ℃, the unit pressure is 3-10 MPa, and the setting time is 10-30 min;

the straw raw material is formed by compounding long straw fibers and short straw fibers;

the length of the long straw fibers is 1-2 cm, and the length of the short straw fibers is less than 1 cm.

2. The straw aerogel flame-retardant insulation board as claimed in claim 1, wherein the straw raw material comprises 10-30% by mass of straw long fibers and 70-90% by mass of straw short fibers.

3. The straw aerogel flame-retardant insulation board according to claim 1 or 2, wherein the moisture content of the straw raw material is less than 10 wt%.

4. The straw aerogel flame-retardant insulation board according to claim 1, wherein the coupling agent is polyvinyl alcohol.

5. The straw aerogel flame-retardant insulation board according to claim 1, wherein the water-soluble silicon source is instant powdery sodium silicate, and the modulus is 2.1-3.4.

6. The straw aerogel flame-retardant insulation board according to claim 1, wherein the calcium source is semi-hydrated gypsum.

7. The preparation method of the straw aerogel flame-retardant insulation board as claimed in any one of claims 1 to 6, characterized by comprising the following steps:

(1) after the straw is dedusted, drying, mechanically grinding to obtain fiber filaments with different lengths, screening to obtain the required long fibers and short fibers of the straw, and compounding the long fibers and the short fibers in proportion to obtain the straw raw material;

(2) firstly, weighing a water-soluble silicon source, a calcium source, the straw raw material in the step (1), polyvinyl alcohol and water in proportion, preparing the water-soluble silicon source and the water into an aqueous solution, and finally stirring the straw raw material, the polyvinyl alcohol, the water-soluble silicon source solution and the calcium source in sequence to obtain a mixed material after uniform mixing;

(3) paving, prepressing and molding the mixed material obtained in the step (2), and solidifying at high temperature and high pressure to obtain a plate blank of the straw aerogel flame-retardant insulation board;

(4) and (4) maintaining, cutting edges and sanding the plate blank obtained in the step (3) to obtain the straw aerogel flame-retardant insulation board finished product plate.

8. The preparation method of the straw aerogel flame-retardant insulation board according to claim 7, wherein the length of the straw fiber after mechanical grinding in the step (1) is not more than 2 cm.

9. The preparation method of the straw aerogel flame-retardant insulation board according to claim 7, wherein the solid content of the water-soluble silicon source solution in the step (2) is 30-40%.

10. The preparation method of the straw aerogel flame-retardant insulation board according to claim 7, wherein the pre-pressing molding in the step (3) is performed under normal temperature and normal pressure until a board blank is molded.

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